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Fast and optimized pages lead to higher visitor engagement, retention, and conversions. The PageSpeed family of tools is designed to help you optimize the performance of your website. PageSpeed Insights products will help you identify performance best practices that can be applied to your site, and PageSpeed optimization tools can help you automate the process.

Page Speed Insights measures the performance of a page for mobile devices and desktop devices. It fetches the url twice, once with a mobile user-agent, and once with a desktop-user agent.

The PageSpeed Score ranges from 0 to 100 points. A higher score is better and a score of 85 or above indicates that the page is performing well. Please note that PageSpeed Insights is being continually improved and so the score will change as we add new rules or improve our analysis.

PageSpeed Insights measures how the page can improve its performance on:

time to above-the-fold load: Elapsed time from the moment a user requests a new page and to the moment the above-the-fold content is rendered by the browser.

time to full page load: Elapsed time from the moment a user requests a new page to the moment the page is fully rendered by the browser.

However, since the performance of a network connection varies considerably, PageSpeed Insights only considers the network-independent aspects of page performance: the server configuration, the HTML structure of a page, and its use of external resources such as images, JavaScript, and CSS. Implementing the suggestions should improve the relative performance of the page. However, the absolute performance of the page will still be dependent upon a user’s network connection.

Each suggestion is rated with a priority indicator to indicate its importance:

Web Performance Best Practices

When you profile a web page with Page Speed, it evaluates the page's conformance to a number of different rules. These rules are general front-end best practices you can apply at any stage of web development. Page Speed provide documentation of each of the rules here, so whether or not you run the Page Speed tool — maybe you're just developing a brand new site and aren't ready to test it — you can refer to these pages at any time. Page Speed give you specific tips and suggestions for how you can best implement the rules and incorporate them into your development process.

About the performance best practices

Page Speed evaluates performance from the client point of view, typically measured as the page load time. This is the lapsed time between the moment a user requests a new page and the moment the page is fully rendered by the browser. The best practices cover many of the steps involved in page load time, including resolving DNS names, setting up TCP connections, transmitting HTTP requests, downloading resources, fetching resources from cache, parsing and executing scripts, and rendering objects on the page. Essentially Page Speed evaluates how well your pages either eliminate these steps altogether, parallelize them, and shorten the time they take to complete. The best practices are grouped into six categories that cover different aspects of page load optimization:

Tutorials

There are many ways to make websites run faster. In this section, you can discover performance best practices that real web professionals employ in their everyday work. These practices have improved the user experience for millions of users and we hope they are useful for other web developers.

You can often reduce the number of bytes of a web page — and speed up the page's download — without changing its appearance or function. Discover three ways to reduce the size of web page content, using Page Speed.

When working with Rich Internet Applications, we write JavaScript that updates the page by changing elements or adding new ones. This is done by working with the DOM, or Document Object Model, and how we do this can affect the speed of our applications.

To the typical user, speed doesn't only mean performance — it means the ability to use your website efficiently. Learn how to deliver effective UI messaging, a crucial part of keeping your users engaged and productive.

In HTML, we can already reduce content size significantly by omitting optional tags. HTML 5, which is still under development, offers us a couple more options to decrease file size beside leaving out optional stuff. This article features some basic measures to reduce content size a bit more, plus the async and defer attributes useful to improve script execution.